Thanks to John Burgeson for the tip on the Astronomy Picture of the Day
composite photo showing the lights around the world. I'll try to use it in
class next week.

Regarding this photo, Jonathan Clarke made a comment that the
International Space Station is not just a Boeing product or a US
project. However, to set the record straight, John and Jonathan, if one
goes to the APOD address cited at the bottom left of this photo, the
correct origin of this picture is the DMSP (Defense Meteorological
Satellites Program) satellite and not the ISS.